When I drag the SeoTools32.xll into a spreadsheet, I get the following diagnostic display:

Initialization [Error] External library could not be registered - Path: bin\SeoTools.dll : BadImageFormatException - Could not load file or assembly ‘file:///C:\Program Files (x86)\SeoTools for Excel\bin\SeoTools.dll’ or one of its dependencies. The module was expected to contain an assembly manifest.